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PHOENIX - With electronic cigarettes gaining popularity, officials in Arizona and nationwide are seeing more cases of people exposed to too much nicotine, not just from inhaling but by spilling or swallowing the liquid drug.

Banner Good Samaritan Poison & Drug Information Center received 24 calls last year about nicotine exposure from e-cigarettes, 13 of them involving children. That's up from 10 cases – four involving children – in 2012.

In the first weeks of this year, the center had received six calls, four involving children.

"It is very concerning," said Dr. Frank LoVecchio, the center's co-medical director.

"The public has to be educated that nicotine is very toxic and has been associated with deaths," he said.

Symptoms of severe nicotine exposure include nausea, excessive salivation, abdominal pain, vomiting, diarrhea, headache, dizziness and irregular heartbeat, according to the U.S. Centers for Disease Control and Prevention.

Poison control centers nationwide reported 438 cases of nicotine exposure from electronic cigarettes in 2012, the latest year that had data available, according to the National Poison Data System. That was up from 256 cases in 2011.

Almost half of the cases in each year involved children ages 5 and younger.

LoVecchio said the cartridges in refillable e-cigarettes hold nicotine equivalent to about two packs of cigarettes, an amount that can kill a toddler who ingests it.

And it's not just swallowing the nicotine that concerns doctors; exposure can occur through the skin as well due to accidentally spilling the liquid from containers, which are easily opened.

Dr. F. Mazda Shirazi, medical director of the Arizona Poison and Drug Information Center, part of the University of Arizona's College of Pharmacy, said the devices need to be dealt with like dangerous medication: kept in locked medicine cabinets, out of the reach of children.

"In a small kid, if they get into the concentrated refills, they can have similar effects of when (nicotine) is used as a pesticide," Shirazi said.

LoVecchio said not a lot is known about the dangers of e-cigarettes, including the effects of secondhand vapor and the amounts of ingredients that can cause cancer.

And then there's the perception that inhaling water vapor and nicotine, a natural substance, makes using e-cigarettes safe.

"We see that many times that the public believes if something is natural or comes from a plant that it shouldn't be harmful," LoVecchio said.

He said the flavors offered for the liquid nicotine refills "almost look like an ice cream store" and are geared toward young adults and children.

"What upsets us at the poison center is that a lot of these liquids are not horrid tasting, in fact they're just the opposite, LoVecchio said. "They are made to taste very good."

An Arizona law enacted last year bans the sale of electronic cigarettes to minors.

But Danny McGoldrick, vice president of the Washington, D.C.-based Campaign for Tobacco-Free Kids, wants more government action, including the Food and Drug Administration regulating flavors and requiring stores to keep the devices behind counters.

"It's the policies we put in place that can really make sure these products are not sold and marketed to kids," he said.

Ray Story, founder and CEO of the Tobacco Vapor Electronic Cigarette Association, said his industry group would support regulations that improve the safety of the devices, such as requiring child-safety caps and child-proof packaging.

"This is an adult product, so it should be sold to adults in a manner consistent to safety standards we are accustomed to," he said.

Shirazi said the increase in parents using e-cigarettes and bringing them into their homes will result in more cases of nicotine exposure among kids in future years.

"It's just a matter of the mathematical growth that it's having," he said.

Shirazi also said he expects more teenagers and adults to get hooked on the devices to their detriment.

"Twenty years down the line they're going to turn around and regret it, but by then the damage is done," he said.